A Singaporean teenager whose video posts and blogs mocking his government and its late founder landed him in jail twice has been detained in the US where he is seeking asylum.

The Human Rights Watch deputy director for Asia, Phil Robertson, called on the US to recognise Amos Yee's asylum claim.

He said he has been consistently harassed by the Singapore government for publicly expressing his views on politics and religion and severely criticising the city-state's leaders, including late prime minister Lee Kuan Yew.

Yee, 18, was imprisoned for six weeks in September on charges of hurting religious feelings of Christians and Muslims after repeatedly breaching bail conditions following a four-week prison sentence he served in July last year on the same charges.

He was also due to be called up for mandatory military service.

Mr Robertson said Yee has faced intensive government surveillance and monitoring of his public and online comments.

"Amos Yee is the sort of classic political dissident that the UN Refugee Convention was designed to protect, and Human Rights Watch hopes the US will recognise his asylum claim," he said.

His US lawyer Sandra Grossman told the South China Morning Post on Saturday that Yee was likely detained at Chicago's O'Hare International Airport because he entered the country on a tourist visa despite an intention to apply for asylum.

She said Yee would have to undergo a "credible fear interview" by an asylum official who would assess if he faces a credible fear of persecution or torture back home.

She said the process usually takes a few days, but the holiday season could delay it. He would then appear before an immigration judge, but that could take years because of backlogs in the immigration system.

Yee, who won a local filmmaking prize aged 13, ruffled feathers in Singapore with a video blog laced with expletives as the city-state was mourning Mr Lee's death in March last year.

Such open criticism and lampooning of leaders is rarely seen in Singapore, where laws are strictly enforced.

The government of the multi-ethnic state says Yee crossed the red line on religion when he mocked Christians and Muslims and the law had to be enforced on him to protect racial and religious harmony.